S-adenosyl-L-methionine-binding protein that acts as an inhibitor of mTORC1 signaling via interaction with the GATOR1 and KICSTOR complexes (PubMed:29123071, PubMed:35776786). Acts as a sensor of S-adenosyl-L-methionine to signal methionine sufficiency to mTORC1: in presence of methionine, binds S-adenosyl-L-methionine, leading to disrupt interaction with the GATOR1 and KICSTOR complexes and promote mTORC1 signaling (PubMed:29123071, PubMed:35776786). Upon methionine starvation, S-adenosyl-L-methionine levels are reduced, thereby promoting the association with GATOR1 and KICSTOR, leading to inhibit mTORC1 signaling (PubMed:29123071, PubMed:35776786). Probably also acts as a S-adenosyl-L-methionine-dependent methyltransferase (Potential). {ECO:0000255|HAMAP-Rule:MF_03044, ECO:0000269|PubMed:29123071, ECO:0000269|PubMed:35776786}. This is the function of SAMTOR (S-adenosylmethionine sensor upstream of mTORC1, ENSG00000164603).